French writer Stéphane Audeguy chose an obscure, but wonderfully eccentric protagonist for his second novel, The Only Son—the philosopher Jean-Jacques Rousseau’s older brother, François, who, disowned by his family, enters the demimonde that was eighteenth-century Paris. In John Cullen’s translation, the sensual decadence of the age is fully conveyed, from the goings-on of a Chinese bathhouse to the squalor in the Tour de la Comté. It’s an exuberant reply to the younger Rousseau’s fabled Confessions.